This invention relates to coating compositions and, more particularly, to coating compositions for fireproofing structural substrates, such as building walls and the like.
There is a well-recognized need for low cost coating compositions which can be applied to surface of structural members including dry wall paneling and synthetic polymeric structural materials, such as Styrofoam and polyurethane, to provide a fireproof barrier coating which is capable of adhering to the surface of the substrate throughout the entire spectrum of anticipated environmental conditions during normal use and a fire. Such a coating composition desirably should be capable of convenient formulation from inexpensive materials and being applied to the substrate in a convenient manner. Also, in order to be safe and effective for a variety of applications, the coating composition should provide a fireproof barrier having the following basic characteristics: (1) high resistance to moisture permeation so as to prevent moisture from migrating to and collecting at the interface between the barrier coating and the substrate, (2) emit very little or no smoke and no appreciable amount of toxic vapors when exposed to open flame and/or elevated temperatures up to 1400.degree. F. and higher, (3) tenaciously adhere to the substrate surface without peeling or cracking when exposed to temperatures ranging from sub-freezing up to 1400.degree. F., or higher, (4) high heat reflectivity so as to minimize the amount of heat allowed to permeate to the substrate, and (5) sufficient hardness to prevent punctures under normal usage conditions. Desirable secondary characteristics include (6) resistance to deterioration by ultraviolet light, (7) resistance to organic solvents, acids and alkaline materials, (8) provide an attractive, decorative finish, (9) ability to completely cover or "hide" substrate surface, and (10) capable of being painted with various types of decorative paints without losing its heat reflectivity and other fireproofing properties.
Prior art coating compositions containing inorganic fire resistant substances typically also include substantial amounts of organic binders, such as asphalt or synthetic polymers, to enhance adhesion of the resultant coating to the substrate. Such organic materials often are quite expensive and/or detract from the fireproofing characteristics of the resultant barrier coating. The coating composition disclosed in my U.S. Pat. No. 4,095,985 issued on June 20, 1978 does not have many of the shortcomings of other prior art compositions because it does not contain organic substances. However, the resultant barrier coating tends to check or crack at elevated temperatures, is vulnerable to attack by solvents, acids and alkaline materials, and tends to allow heat to permeate to the substrate surface.